Microwave heating apparatus

Abstract

A microwave heating apparatus comprising an oven cavity, a magnetron connected with the oven cavity through a waveguide, an electromagnetic wave mode stirrer provided in the oven cavity, and a frequency pulling generator located in the waveguide and moving independently of the movement of the electromagnetic wave mode stirrer.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. A microwave heating apparatus for heating an object comprising: an oven enclosure having a microwave coupling inlet;   a magnetron for generating a microwave at the oscillating frequency of the magnetron;   a waveguide having one end connected to the microwave coupling inlet and the other end connected to the magnetron for transmitting a microwave from the magnetron into the oven enclosure;   drivable means disposed inside the oven enclosure for stirring the pattern of the electromagnetic field of the microwave transmitted into the oven enclosure;   drivable means disposed inside the waveguide for frequency pulling the oscillating frequency of the magnetron; and   means for driving the frequency pulling means independently of the stirring means.   
     
     
       2. The microwave heating apparatus recited in claim 1 wherein the driving means comprises an electric motor. 
     
     
       3. The microwave heating apparatus recited in claim 1 wherein the driving means comprises flowing air. 
     
     
       4. The microwave heating apparatus recited in claim 1 wherein the driving means comprises: a first motor for driving the frequency pulling means; and   a second motor for driving the stirring means; and   means for rotating the first and second motors separately so that their rates of rotation differ from each other.   
     
     
       5. The microwave heating apparatus recited in claim 1 wherein each of the stirring means and the frequency pulling means has at least one wing of ferroelectric material. 
     
     
       6. The microwave heating apparatus recited in claim 1 wherein each of the stirring means and the frequency pulling means has a plurality of wings of ferroelectric material and the wings of the frequency pulling means are fewer than those of the stirring means. 
     
     
       7. The microwave heating apparatus recited in claim 1 wherein the stirrer means comprises a rotatable holder for the object to be heated. 
     
     
       8. The microwave heating apparatus recited in claim 1 wherein the frequency pulling means is reciprocatable. 
     
     
       9. A microwave heating apparatus comprising an oven cavity, a waveguide, a magnetron connected with the oven cavity through the waveguide, and a electromagnetic wave mode stirrer, wherein a frequency pulling generator to vary the oscillating frequency of the magnetron by the aid of frequency pulling phenomenon is provided in the waveguide and moves independently of the movement of the electromagnetic wave mode stirrer. 
     
     
       10. A microwave heating apparatus according to claim 9, wherein the electromagnetic wave mode stirrer and the frequency pulling generator are driven mutually independently by an electric motor or a flowing air. 
     
     
       11. A microwave heating apparatus according to claim 9, wherein the frequency pulling generator is driven by a flowing air which cools the magnetron. 
     
     
       12. A microwave heating apparatus according to claim 9, wherein both the electromagnetic wave mode stirrer and the frequency pulling generator have motors respectively and are rotated separately so that their rates of rotation differ from each other. 
     
     
       13. A microwave heating apparatus according to claim 9, wherein both the electromagnetic wave mode stirrer and frequency pulling generator have a wing of ferroelectric material. 
     
     
       14. A microwave heating apparatus according to claim 13, wherein the wings of the frequency pulling generator are fewer than that of the electromagnetic wave mode stirrer. 
     
     
       15. A microwave heating apparatus according to claim 9, wherein the electromagnetic wave mode stirrer rotates holding the object being heated. 
     
     
       16. A microwave heating apparatus according to claim 9, wherein the frequency pulling generator moves reciprocately. 
     
     
       17. A microwave heating apparatus according to claim 9, wherein the waveguide is branched off and each of the branched waveguides comprises a frequency pulling generator therein. 
     
     
       18. A microwave heating apparatus according to claim 17, wherein a plurality of frequency pulling generators in the branched waveguides and the electromagnetic wave mode stirrer in the oven cavity move independently of one another.